Assignment of Peaks

Peaks can be assigned by using the Assignment Panel in the Assignment menu. Alternatively, you can access it by holding the mouse over a peak and pressing a or doing Right Click / Assign / Assign Spectrum. The Assignment Panel can also be called directly from a Peak Table in the Peak Lists pop-up. The Assignment Panel will show a field for each dimension of the peak. On the left there is the information on isotope type and chemical shift and what assignments have been made for the peak. On the right hand side are possible assignment options. Note that more than one assignment can be made for a single peak (as it may be the result of two overlapping resonances).

Several options are available. Of particular note are the Double Tolerances and Correlated Dims options. By default each spectrum has certain tolerances for each dimension within which Analysis will look for assignment options. Sometimes it is useful to double this when doing assignments, if the peaks are slightly off in the different spectra. The tolerances can be changed for spectra by calling the Tolerances pop-up from within the Edit Spectrum pop-up.

The Correlated Dims option makes use of the fact that the experiment type is known and that for some experiments certain dimensions have to belong to the same spin system. For example for a peak in an HSQC spectrum the two dimensions (H and N) have to belong to the same spin system (residue). Thus, if Correlated Dims is selected, only those options are shown where both dimension fit to the same spin system – a useful way of reducing your assignment options quickly.

If you are doing assignments in the solid state and are using a glycerol labelling scheme, then you can select this using the Labelling Scheme drop-down menu.